Panoramic atrial mapping with basket catheters: A quantitative analysis to optimize practice, patient selection, and catheter choice.

INTRODUCTION: Panoramic mapping with basket catheters has been used to map atrial fibrillation (AF). However, the limited tissue contact and coverage achieved has raised concerns. METHODS AND RESULTS: Patients undergoing catheter ablation for atrial tachycardia (AT) and persistent AF were recruited. Unipolar signals were recorded with the Constellation or FIRMap catheters. The proportion and distribution of anatomical coverage by the catheters was determined and tissue contact achieved measured. The impact of catheter position, left atrium (LA) size, and bipolar voltage were evaluated. Forty patients were recruited (20 Constellation and 20 FIRMap). The LA coverage achieved with the FIRMap catheter compared to the Constellation catheter was greater (76.9 ± 12.9% vs. 50.8 ± 10.3%; P < 0.001), with better septal coverage (66.8 ± 20.9% vs. 15.5 ± 12.0%; P < 0.001). A greater number of electrodes recorded peak-to-peak electrogram amplitude of ≥0.5 mV (84.2% vs. 62.8%; P < 0.001). Positioning the catheter tip at or posterior to LA appendage ridge gave better coverage than a more anterior position (P = 0.001). Increasing LA area correlated inversely with coverage (P < 0.001) and contact (P = 0.002) despite patient-specific basket catheter sizing. An LA area of >30 cm2 and mean bipolar voltage of <0.3 mV was associated with reduction in coverage and contact (both P < 0.001). There was a significant difference in AT/AF freedom during follow-up in the FIRMap versus Constellation group (13/13 vs. 8/12; P = 0.04). CONCLUSIONS: The FIRMap is superior to the Constellation catheter in terms of LA coverage and contact. Optimizing catheter position and appropriate patient selection based on no more than moderately dilated or scarred atria will also facilitate mapping with basket catheters.

Standardized unfold mapping: a technique to permit left atrial regional data display and analysis.

PURPOSE: Left atrial arrhythmia substrate assessment can involve multiple imaging and electrical modalities, but visual analysis of data on 3D surfaces is time-consuming and suffers from limited reproducibility. Unfold maps (e.g., the left ventricular bull's eye plot) allow 2D visualization, facilitate multimodal data representation, and provide a common reference space for inter-subject comparison. The aim of this work is to develop a method for automatic representation of multimodal information on a left atrial standardized unfold map (LA-SUM). METHODS: The LA-SUM technique was developed and validated using 18 electroanatomic mapping (EAM) LA geometries before being applied to ten cardiac magnetic resonance/EAM paired geometries. The LA-SUM was defined as an unfold template of an average LA mesh, and registration of clinical data to this mesh facilitated creation of new LA-SUMs by surface parameterization. RESULTS: The LA-SUM represents 24 LA regions on a flattened surface. Intra-observer variability of LA-SUMs for both EAM and CMR datasets was minimal; root-mean square difference of 0.008 ± 0.010 and 0.007 ± 0.005 ms (local activation time maps), 0.068 ± 0.063 gs (force-time integral maps), and 0.031 ± 0.026 (CMR LGE signal intensity maps). Following validation, LA-SUMs were used for automatic quantification of post-ablation scar formation using CMR imaging, demonstrating a weak but significant relationship between ablation force-time integral and scar coverage (R 2 = 0.18, P < 0.0001). CONCLUSIONS: The proposed LA-SUM displays an integrated unfold map for multimodal information. The method is applicable to any LA surface, including those derived from imaging and EAM systems. The LA-SUM would facilitate standardization of future research studies involving segmental analysis of the LA.

Validation of electrical ostial pulmonary vein isolation verified with a spiral inner lumen mapping catheter during second-generation cryoballoon ablation.

BACKGROUND: Achieve catheters are cryoballoon guidewires that enable pulmonary vein (PV) potential mapping. The single catheter approach in conjunction with the Achieve catheter is currently standard practice in second-generation cryoballoon ablation, yet circumferential mapping catheters are the gold standard for evaluating PV isolation (PVI). The study sought to validate the ostial PVI verified by an Achieve catheter alone. METHODS: One hundred fifty-one paroxysmal atrial fibrillation patients undergoing PVI using exclusively 28-mm second-generation cryoballoons were enrolled. PV recordings were analyzed during (real-time recordings) and after cryoballoon applications with 20-mm Achieve mapping catheters, and subsequently validated by 20-mm conventional circumferential mapping catheters. RESULTS: Out of 596 PVs, 576 (96.6%) were isolated using cryoballoons, and 20 required touch-up ablation. PVI was verified during cryoballoon applications with real-time monitoring in 299, and after applications in 280 PVs by Achieve catheters alone. The time-to-isolation was 27.2 ± 22.0 seconds. Validation with standard circumferential mapping catheters confirmed ostial PVIs in 296 of 299 (99.0%) PVs that real-time PVI was obtained during applications, and in 242 of 280 (86.5%) PVs that PV activities were not visible during applications and PVI was verified after the applications. The accuracy of ostial PVIs with Achieve catheters in PVs without obtaining real-time PV recordings was 40/47 (85.1%), 58/65 (89.2%), 77/79 (97.5%), 61/81 (75.3%), and 6/8 (75.0%) in left superior, left inferior, right superior, right inferior, and left common PVs, respectively. CONCLUSIONS: In second-generation 28-mm cryoballoon ablation, verification of ostial PVIs using Achieve mapping catheters alone might not be sufficient to accurately confirm an ostial PVI when real-time PVI was not obtained.

In vivo validation of a novel algorithm for automatic premature ventricular contractions recognition.

INTRODUCTION: Template-matching algorithms are routinely used in the catheter ablation of patients with premature ventricular contractions (PVCs). However, systematic analysis of the accuracy and spatial resolution of such systems is lacking. Therefore, the aim of this evaluation was to perform a systematic in vivo validation of performance of a novel automated template-matching algorithm. METHODS AND RESULTS: In a porcine model, paced beats simulating PVCs from different origins were investigated. The ability to discriminate between sinus rhythm and PVCs was tested by simulating PVCs using sequential pacing from different cardiac chambers. The accuracy of the algorithm in correctly classifying PVCs was reviewed by an independent investigator. In addition, the spatial resolution of pace matching was evaluated by assessing the QRS morphology discrimination at a distance of 0, 2, 4, and 6 mm of a simulated PVCs focus. The specificity of the algorithm for recognizing simulated PVCs was 99.6% and the sensitivity was 85.3%. There was a significant difference in the discrimination metric discrimination metric (with 0% being a perfect match and 100% being no correlation) between PVC origin (median 0%, interquartile range (IQR) 0-2%) versus at 2 mm (5%, IQR 2-7%), 4 mm (16%, IQR 11-21%), and 6 mm (24%, IQR 19-28%, P < 0.001 for all). The c-statistic for discrimination between PVC origin and a distance ≥ 2 mm was 0.93. CONCLUSIONS: Automated template matching had high specificity and sensitivity, with good spatial discrimination and a pace-mapping resolution in range of 2 mm. Clinical application of this algorithm may assist in the interventional treatment of patients with PVCs.

Quantitative analysis of surface electromyography during epileptic and nonepileptic convulsive seizures.

OBJECTIVE: To investigate the characteristics of sustained muscle activation during convulsive epileptic and psychogenic nonepileptic seizures (PNES), as compared to voluntary muscle activation. The main goal was to find surface electromyography (EMG) features that can distinguish between convulsive epileptic seizures and convulsive PNES. METHODS: In this case-control study, surface EMG was recorded from the deltoid muscles during long-term video-electroencephalography (EEG) monitoring in 25 patients and in 21 healthy controls. A total of 46 clinical episodes were recorded: 28 generalized tonic-clonic seizures (GTCS) from 14 patients with epilepsy, and 18 convulsive PNES from 12 patients (one patient had both GTCS and PNES). The healthy controls were simulating GTCS. To quantitatively characterize the signals we calculated the following parameters: root mean square (RMS) of the amplitude, median frequency (MF), coherence, and duration of the seizures, of the clonic EMG discharges, and of the silent periods between the cloni. Based on wavelet analysis, we distinguished between a low-frequency component (LF 2-8 Hz) and a high-frequency component (HF 64-256 Hz). RESULTS: Duration of the seizure, and separation between the tonic and the clonic phases distinguished at group-level but not at individual level between convulsive PNES and GTCS. RMS, temporal dynamics of the HF/LF ratio, and the evolution of the silent periods differentiated between epileptic and nonepileptic convulsive seizures at the individual level. A combination between HF/LF ratio and RMS separated all PNES from the GTCS. A blinded review of the EMG features distinguished correctly between GTCS and convulsive PNES in all cases. The HF/LF ratio and the RMS of the PNES were smaller compared to the simulated seizures. SIGNIFICANCE: In addition to providing insight into the mechanism of muscle activation during convulsive PNES, these results have diagnostic significance, at the individual level. Surface EMG features can accurately distinguish convulsive epileptic from nonepileptic psychogenic seizures, even in PNES cases without rhythmic clonic movements.

Rotor stability separates sustained ventricular fibrillation from self-terminating episodes in humans.

OBJECTIVES: This study mapped human ventricular fibrillation (VF) to define mechanistic differences between episodes requiring defibrillation versus those that spontaneously terminate. BACKGROUND: VF is a leading cause of mortality; yet, episodes may also self-terminate. We hypothesized that the initial maintenance of human VF is dependent upon the formation and stability of VF rotors. METHODS: We enrolled 26 consecutive patients (age 64 ± 10 years, n = 13 with left ventricular dysfunction) during ablation procedures for ventricular arrhythmias, using 64-electrode basket catheters in both ventricles to map VF prior to prompt defibrillation per the institutional review board-approved protocol. A total of 52 inductions were attempted, and 36 VF episodes were observed. Phase analysis was applied to identify biventricular rotors in the first 10 s or until VF terminated, whichever came first (11.4 ± 2.9 s to defibrillator charging). RESULTS: Rotors were present in 16 of 19 patients with VF and in all patients with sustained VF. Sustained, but not self-limiting VF, was characterized by greater rotor stability: 1) rotors were present in 68 ± 17% of cycles in sustained VF versus 11 ± 18% of cycles in self-limiting VF (p < 0.001); and 2) maximum continuous rotations were greater in sustained (17 ± 11, range 7 to 48) versus self-limiting VF (1.1 ± 1.4, range 0 to 4, p < 0.001). Additionally, biventricular rotor locations in sustained VF were conserved across multiple inductions (7 of 7 patients, p = 0.025). CONCLUSIONS: In patients with and without structural heart disease, the formation of stable rotors identifies individuals whose VF requires defibrillation from those in whom VF spontaneously self-terminates. Future work should define the mechanisms that stabilize rotors and evaluate whether rotor modulation may reduce subsequent VF risk.

Validity of the surface electrocardiogram criteria for right ventricular hypertrophy: the MESA-RV Study (Multi-Ethnic Study of Atherosclerosis-Right Ventricle).

OBJECTIVES: The study aimed to assess the diagnostic properties of electrocardiographic (ECG) criteria for right ventricular hypertrophy (RVH) measured by cardiac magnetic resonance imaging (cMRI) in adults without clinical cardiovascular disease. BACKGROUND: Current ECG criteria for RVH were based on cadaveric dissection in small studies. METHODS: MESA (Multi-Ethnic Study of Atherosclerosis) performed cMRIs with complete right ventricle (RV) interpretation on 4,062 participants without clinical cardiovascular disease. Endocardial margins of the RV were manually contoured on diastolic and systolic images. The ECG screening criteria for RVH from the 2009 American Heart Association Recommendations for Standardization and Interpretation of the ECG were examined in participants with and without left ventricular (LV) hypertrophy or reduced ejection fraction. RVH was defined using sex-specific normative equations based on age, height, and weight. RESULTS: The study sample with normal LV morphology and function (n = 3,719) was age 61.3 ± 10.0 years, 53.5% female, 39.6% Caucasian, 25.5% African American, 21.9% Hispanic, and 13.0% Asian. The mean body mass index was 27.9 ± 5.0 kg/m(2). A total of 6% had RVH, which was generally mild. Traditional ECG criteria were specific (many >95%) but had low sensitivity for RVH by cMRI. The positive predictive values were not sufficiently high as to be clinically useful (maximum 12%). The results did not differ based on age, sex, race, or smoking status, or with the inclusion of participants with abnormal LV mass or function. Classification and regression tree analysis revealed that no combination of ECG variables was better than the criteria used singly. CONCLUSIONS: The recommended ECG screening criteria for RVH are not sufficiently sensitive or specific for screening for mild RVH in adults without clinical cardiovascular disease.

Accuracy assessment of catheter guidance technology in electrophysiology procedures: a comparison of a new 3D-based fluoroscopy navigation system to current electroanatomic mapping systems.

BACKGROUND: With increasing complexity in electrophysiology (EP) procedures, the use of electroanatomic mapping systems (EAMS) as a supplement to fluoroscopy has become common practice. This is the first study that evaluates spatial and point localization accuracy for 2 current EAMS, CARTO3(®) (Biosense Webster, Diamond Bar, CA, USA) and EnSite Velocity(®) (St. Jude Medical Inc., St. Paul, MN, USA), and for a novel overlay guidance (OG) software (Siemens AG, Forchheim, Germany) in a phantom experiment. METHODS AND RESULTS: A C-arm CT scan was performed on an acrylic phantom containing holes and location markers. Spatial accuracy was assessed for each system using distance measurements involving known markers inside the phantom and properly placed catheters. Anatomical maps of the phantom were acquired by each EAMS, whereas the 3D-based OG software superimposed an overlay image of the phantom, segmented from the C-arm CT data set, onto biplane fluoroscopy. Registration processes and landmark measurements quantitatively assessed the spatial accuracy of each technology with respect to the ground truth phantom. Point localization performance was 0.49 ± 0.25 mm in OG, 0.46 ± 0.17 mm in CARTO3(®) and 0.79 ± 0.83 mm in EnSite(®) . The registration offset between virtual visualization and reality was 1.10 ± 0.52 mm in OG, 1.62 ± 0.77 mm in CARTO3(®) and 2.02 ± 1.21 mm in EnSite(®) . The offset to phantom C-arm CT landmark measurements was 0.30 ± 0.26 mm in OG, 0.24 ± 0.21 mm in CARTO3(®) and 1.32 ± 0.98 mm in EnSite(®) . CONCLUSIONS: Each of the evaluated EP guidance systems showed a high level of accuracy; the observed offsets between the virtual 3D visualization and the real phantom were below a clinically relevant threshold of 3 mm.

Diagnostic value of the left atrial electrical potentials detected by body surface potential mapping in the prediction of coronary artery disease.

BACKGROUND: The electrocardiographic diagnosis of significant coronary artery stenosis (CAD) is often based on the investigation of the left ventricular repolarization changes during exercise ECG stress test (EST). Our aim was to prove that the electric activity of the left atrium can indicate the ischemic damage of the left ventricle, and furthermore, it is able to indicate CAD without exercise. METHODS AND RESULTS: Patients with chest complaints but without evidence of acute coronary syndrome were investigated by EST and body surface potential mapping (BSPM, 63 leads). CAD was proven in 45 cases (32 men, years 40-76) and excluded in 50 cases (35 men, years 38-72) with coronary angiography. Left atrial electric potentials (EP-LA) before and after 0.08 mg sublingual nitroglycerine administration differed significantly (p<0.001) in the two groups. According to Fischer linear discriminant analysis, this difference in % (EP-LA(d%)) was the best separating parameter: below limit of -14.17% (CAD prevalence was considered) this parameter predicted CAD with 93% sensitivity, 100% specificity, >10 positive and 0.05 negative likelihood ratio (weighted for prevalence). The EST predicted CAD with 71% sensitivity, 78% specificity, 2.43 positive and 0.28 negative likelihood ratios. CONCLUSION: The electrical activity changes of the left atrium seemed to be suitable to predict CAD as an EST-alternative resting method.

Incremental benefit of 80-lead electrocardiogram body surface mapping over the 12-lead electrocardiogram in the detection of acute coronary syndromes in patients without ST-elevation myocardial infarction: Results from the Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT MI) trial.

BACKGROUND: The initial 12-lead (12L) electrocardiogram (ECG) has low sensitivity to detect myocardial infarction (MI) and acute coronary syndromes (ACS) in the emergency department (ED). Yet, early therapies in these patients have been shown to improve outcomes. OBJECTIVES: The Optimal Cardiovascular Diagnostic Evaluation Enabling Faster Treatment of Myocardial Infarction (OCCULT-MI) trial was a multicenter trial comparing a novel 80-lead mapping system (80L) to standard 12L ECG in patients with chest pain and presumed ACS. This secondary analysis analyzed the incremental value of the 80L over the 12L in the detection of high-risk ECG abnormalities (ST-segment elevation or ST depression) in patients with MI and ACS, after eliminating all patients diagnosed with ST-elevation MI (STEMI) by 12L ECG. METHODS: Chest pain patients presenting to one of 12 academic EDs were diagnosed and treated according to the standard care of that site and its clinicians; the clinicians were blinded to 80L results. MI was defined by discharge diagnosis of non-ST-elevation MI (NSTEMI) or unstable angina (UA) with an elevated troponin. ACS was defined as discharge diagnosis of NSTEMI or UA with at least one positive test result (troponin, stress test, angiogram) or revascularization procedure. RESULTS: Of the 1,830 patients enrolled in the trial, 91 patients with physician-diagnosed STEMI and 225 patients with missing 80L or 12L data were eliminated from the analysis; no discharge diagnosis was available for one additional patient. Of the remaining 1,513 patients, 408 had ACS, 206 had MI, and one had missing status. The sensitivity of the 80L was significantly higher than that of the 12L for detecting MI (19.4% vs. 10.4%, p = 0.0014) and ACS (12.3% vs. 7.1%, p = 0.0025). Specificities remained high for both tests, but were somewhat lower for 80L than for 12L for detecting both MI and ACS. Negative and positive likelihood ratios (LR) were not statistically different between groups. In patients with severe disease (defined by stenosis > 70% at catheterization, percutaneous coronary intervention, coronary artery bypass graft, or death from any cause), the 80L had significantly higher sensitivity for detecting MI (with equivalent specificity), but not ACS. CONCLUSIONS: Among patients without ST elevation on the 12L ECG, the 80L body surface mapping technology detects more patients with MI or ACS than the 12L, while maintaining a high degree of specificity.

Usefulness of a limited linear ablation of post-myocardial infarction ventricular tachycardia using a standardized approach based on sinus rhythm mapping.

The ablation of ventricular tachycardia (VT) can be achieved using anatomically guided approaches using differentiated mapping and ablation techniques. The aim of this study was to evaluate the efficacy of limited linear ablation in the VT exit region identified during sinus rhythm mapping alone. One hundred fifteen consecutive patients presenting for ablation of post-myocardial infarction VT were included. After induction of the target VT during invasive electrophysiology, left ventricular substrate mapping during sinus rhythm to identify scar and border zone on the basis of endocardial bipolar voltage was performed. The exit site of the target VT was regionalized by a simplified vector pace mapping approach and targeted using limited linear ablation within the scar border zone. Seventy-seven percent of all inducible VT was successfully ablated. In 71 patients (62%), no sustained VT was inducible at the end of ablation procedure (complete success). During a median follow-up period of 16 + or - 10 months, 89 patients (77%) had no documented sustained ventricular arrhythmia. Seven patients (2%) had recurrences of the initially ablated VT, and 16 (14%) had new-onset VT. Patients with complete success had a significantly lower number of ventricular arrhythmia reoccurrences than patients with incomplete ablation success (11% vs 37%, p = 0.002). In conclusion, postinfarct VT was effectively ablated in 97% of patients without mapping during ongoing VT using a simplified regional linear ablation approach targeting the scar border zone. Freedom from any ventricular arrhythmia was achieved in 77% of patients during midterm follow-up.

[Relationship between reference point potential and potential distribution of normal electrocardial field on the thoracic surface of healthy individuals].

OBJECTIVE: To explore the effect of reference point on the potential distribution of normal cardioeleclric field of healthy individuals. METHODS: Two different reference points including central terminal and right forehead were applied to record electrocardiogram simultaneously from 15 testing points (V(1)-V(6), V(7)-V(9), V(3R)-V(8R)) of Wilson lead (RL) and the same testing points (HV(1)-HV(9), HV(3R)-HV(8R)) of head-chest (HC) lead around the torso of healthy individuals. Chi-square test was performed to observe statistical difference between the HCECGs and RLECGs according to different shapes of QRS and T waves. RESULTS: Among 120 healthy individuals, deformed ECGs appeared in V(1) and HV(3R)-HV(8R) leads, with 20% (24/120) inverted T wave in V(1) lead, 100% (120/120) in V(3R)-V(8R) leads, wide or deep Q wave 100% (120/120) in V(4R)-V(8R) leads. However, in the corresponding HC-lead system, T waves were all positive, and QRS waves were upright as the pattern of rs, RS or qRs. There was statistical difference in the form of ECG between V(1), V(3R)-V(8R) of Wilson lead and the corresponding HC-lead (P<0.05). The distribution of normal cardioeleclric field related to QRS-T wave was of all-round outward shape by HC-lead, and of roughly bipolar shape by Wilson lead for inverted QRS-T wave on the right thoracic surface. CONCLUSION: The normal distribution of electrocardial field is determined by the potential of the reference point. The forehead of HC-lead seems to be better than the central terminal as the reference point of the lead system.

Potential solutions for providing standard electrocardiogram recordings from nonstandard recording sites.

For a 12-lead resting electrocardiogram (ECG) to be considered "standard," limb electrodes should be placed distally on the limbs. When resting ECGs are taken in conjunction with an ECG-monitoring situation, so-called monitoring sites (as described by Mason and Likar and also others) on the torso are used. Numerous publication have indicated that these ECGs are not identical with those recorded from distal sites, and this prohibits application of visual or computer-based interpretation criteria as well as serial comparison with standard ECGs. Loss of Q waves diagnostic for inferior wall myocardial infarction, as well as marked differences in frontal plane electrical axis, is the most commonly encountered problem with torso-recorded ECGs. This overview suggests 4 possible solutions to this dilemma.

Reconstruction of standard 12-lead electrocardiograms from 12-lead electrocardiograms recorded with the Mason-Likar electrode configuration.

Electrocardiograms (ECGs) made with Mason-Likar electrode configuration (ML-ECGs) show well-known differences from standard 12-lead ECGs (Std-ECGs). We recorded, simultaneously, Std-ECGs and ML-ECGs in 180 subjects. Using these ECGs, 8 x 8 individual and general conversion matrices were created by linear regression, and standard ECGs were reconstructed from ML-ECGs using these matrices. The performance of the matrices was assessed by the root mean square differences between the original Std-ECGs and the reconstructed standard ECGs, by the differences in major ECG parameters, and by comparison of computer-generated diagnostic statements. As a result, we conclude that, based on the root mean square differences, reconstructions with 8 x 8 individual matrices perform significantly better than reconstructions with the group matrix and perform equally well with respect to the calculation of major electrocardiographic parameters, which gives an improved reliability of the QRS frontal axis and the maximal QRS and T amplitudes. Both types of matrices were able to reverse the underdiagnosis of inferior myocardial infarctions and the erroneous statements about the QRS frontal axis that arose in the ECGs that were made by using the Mason-Likar electrode positions.

Supplemented standard 12-lead electrocardiogram for optimal diagnosis and reconstruction of significant body surface map patterns.

In this study, based on 120-lead body surface potential maps (BSPMs), we explored the improvement in electrocardiogram (ECG) diagnosis obtained by adding additional leads and using estimation of unmeasured leads. We found that adding a few leads observed to be optimal for diagnosis or signal capture combined with the existing 12-lead ECG improves diagnostic performance. Separately, using reconstruction (estimation) of BSPMs and using diagnostic criteria derived for maps also improve diagnostic performance over that provided by the recorded 12-lead ECG alone. Combining these 2 ideas, namely, addition of optimal leads and estimation of BSPMs improves performance even more.